Locking device for electrical contacts.



J. DE R. KIELLAND.

LOCKING DEVICE FOR ELECTRICAL GONTAGTS.

APPLICATION FILED D3012, 1911.

Patented Apr.28,1914,

O. nnnu n In! 0 v JAKOB DE RYTTER KIELLAND, OF CHRISTIANIA, NQRWAY, ASSIGNOR T0 BENJAMIN ELECTRIC MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

LOCKING DEVICE FOR ELECTRICAL CONTACTS.

Specification of Letters Patent.

Patented Apr. -28, 1914.

Application filed December 12, 1911. Serial No. 665,273.

To all whom it may concern 4 Be it known that I, JAKOB on RYTTER KIELLAND, a subject of the King of Norway, residing at Christiania, Norway, have in vented certain new and useful Improvements in Locking Devices for Electrical Contacts; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

My invention relates to a means in contact devices, especially in incandescent lamp holders, for locking the member inserted inthe holder, and has for its object to prevent said member from being loosened for instance through shakings or vibrations, or from being wrongfully removed. This lat ter provision has become of special importance, since the valuable metal wire lamps have come into common use; for it frequently occurs that such lamps are stolen, and often it is not possible to prevent this at distant places without an expensive supervision.

The invention is illustrated in the accompanying drawing, which represents a form of incandescent lamp holder embodying the invention.

Figure 1 is a longitudinal section through the holder, Fig. 2 a plan view of its insulating'ring. Fig. 3 illustrates a tool for detaching the lamp.

Fig. i byway of example shows an ordinary Edison holder furnished with the said locking device. I member generally formed with screwthreads and serving as a nut for the screwthreads provided on thelamp cap, is entirely or partly replaced by a helical spring a of any conductive and elastic material and having such aform that it can serve as a nut for the screw-threads of the glow-lamp cap. The extremity Z) or a portion of the spring is fast with the metal piece connectedwith the current-carrying contact of the holder, while the other extremity of the spring is free so that the spring may be made to exert its spring action with a shorter or onger portion of its length or with its whole length. Such springs serving to receive the glow-lamp cap are in themselves well In the holder the metal known. 'According to the present invention, however, the last turns of the spring located near the free end of the same are formed with a smaller diameter than the remaining turns corresponding to the diameter of the screw-threads of the glowla'mp cap.

In screwing in the lamp the spring will open to a certain extent and the cap may be screwed home without difiiculty. But if it is now attempted to unscrew the lamp, such operation is rendered impossible, because the spring now acts as a kind of band brake the free end 0, which firmly engages the screw-threads of the glow-lamp cap, being pulled along with the same so that the spring will thereby be caused to engage the threads always more firmly the greater. the force used in attempting to unscrew the lamp, and the lamp would finally burst without being successfully unscrewed. The

object mentioned in the preamble, to prevent the incandescent lamp from getting loose or from being wrongfully removed, is thus" attained. Now, to enable the lamp. to be unscrewed, the holder at its lower portion is furnished with a releasing device which in the present instance is mounted on the in-' sulating ring (Fig. 2) and consists of a' small pin or hook (Z which is so arranged as to abut against the end 0 of the spring on being screwed a little further on thereby suspending or reducing the locking action of said spring, in that the latter will therebybe somewhat extended, whereupon the lamp maybe unscrewed without difiiculty. Even if a thief were acquainted with said releasing device, still it .will be very difficult to him to unscrew the lamp. The longer time required is, however, bf no consequence in the normal exchange of lamps, as such an exchange only has 'to take place once in a year or still more unfrequently.- Said re leasing device may also be provlded as abutton adjustably mounted on theholder sleeve or in any suitable manner. A wrongful removal of the lamp may also be prevented by using ordinary insulating rings without a projection and employing to release. the lamp a tool (Fig. 3.) especially adapted for the purpose the extremity 6 ing the pin or projectionoL.

The present invention may of course also be applied to other devices resembling a (Fig. 3) of the tool, for 'instance,-replac-' lamp holder, for instance to contact cou plings and the like in which it is desired to secure the contact or to prevent a Wrongful unscrewing operation Ithas to be noted that the present invention does not relate to the use of helical springs as a braking means generally, but only, as described, to the use thereof in electric lamp holders and similar electric contacts in conjunction with a device for suspending or reducing the locking action oi the spring.

Claims:

1. A device for locking; contact-couplings comprising a conductive helical. spring serv ing as a not for the screw-threads of one of the couplings and having the turns or part of turn located near the free end of the same formed with a smaller diameter than the remaining turns.

2. A device for locking contact-couplings comprising a conductive helical spring serving as a nut for the screw-threads of one of the couplings and having the last turns vor part of turn'located near the free end of the same formed with a smaller diameter thanthe remaining turns, and an insulating ring, having a projection forthe unlocking; of the spring by a movement against the end of the sprin 3. A- locking device of the character described comprising an externally screwthreaded member, a socket a spiral spring fixed atone end in the socket and adapted eeann? to engage the threads of said member, the

free end portion of said spring being of,

smaller diameter than the other portion, and means to enlarge the smaller diameter, for the purpose specified.

l. A locking device oi the character dcscrihed xcomprising an externally screwthreaded member, a socket, a spiral spring fixed at one end in the socket and adapted to engagethe threads of said niemher the tree end portion of said spring being of smaller diameter than the other portion, and means adapted to engage the free end of the spring to extend the smaller diame ter oi the latter, for the purpose specified.

5. it locking device of the character described comprising an externally screw threaded member, a socket, a spiral spring fixed at one end in the socket and adapted to engage the threads of said member, the free end portion of said spring; being;- of smaller diameter than the other portion, and means on the socket adapted to engage the free end of the spring to extend the smaller diameter of the latter, for the purpose specified.

In testimony that I claim the foregoing as my invention, l have signed my name in presence of two subscribing- Witnesses. 

